Scale-reducing additive for automatic dishwashing systems

Abstract

An automatic dishwashing detergent composition having at least two components. The first component is a polymer containing polymerized residues of at least one C 3 -C 6 carboxylic acid monomer and a hydroxy end group. The second component is a biodegradable builder selected from among nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, glycine-N,N-diacetic acid, methylglycine-N,N-diacetic acid, 2-hydroxyethyliminodiacetic acid, glutamic acid-N,N-diacetic acid, 3-hydroxy-2,2′-iminodisuccinate, S,S-ethylenediaminedisuccinate aspartic acid-diacetic acid, N,N′-ethylenediamine disuccinic acid, iminodisuccinic acid, aspartic acid, aspartic acid-N,N-diacetate, beta-alaninediacetic acid, polyaspartic acid, salts thereof and combinations thereof.

The invention claimed is: 
     
       1. An automatic dishwashing detergent composition comprising:
 (a) from 2-8 wt % of a polymer comprising a hydroxy end group and polymerized residues of C 3 -C 6  carboxylic acid monomers, which comprise:
 (i) 65-72 weight % acrylic acid, 
 (ii) 15-25 weight % methacrylic acid, and 
 (iii) 8-13 weight % maleic acid, 
 
 
       wherein the total of the weight percents of said polymerized residues of monomers (i), (ii) and (iii) is at least 99 weight percent of said polymer, based on the total weight of the polymer, and wherein said polymer (a) comprises no polymerized derivatives of aminoacrylol, alkoxylate or ethoxylate monomers; and
 (b) at least 5 weight %, and no more than 20 weight % of a biodegradable builder selected from the group consisting of glycine-N,N-diacetic acid, methylglycine-N,N-diacetic acid, glutamic acid-N,N-diacetic acid, salts thereof and combinations thereof; 
 
       wherein the polymer has less than 5 mole % sulfonic acid monomer and the detergent composition comprises less than 0.5 wt % phosphorus; and wherein the detergent composition comprises at least 6 wt % silicates and no more than 34 wt % total carbonates. 
     
     
       2. The composition of  claim 1  in which the polymer has Mw from 5,000 to no greater than 20,000. 
     
     
       3. The composition of  claim 2  in which the polymer has less than 1 mole % sulfonic acid monomer residues. 
     
     
       4. The composition of  claim 3  in which the polymer has Mw from 10,000 to no greater than 20,000.